In a damper device (called a piston damper and the like) comprising the cylinder body and the piston body, there is a damper device in which a ventilation path is formed in a closing portion of the cylinder body facing the piston body, and a shaft portion of a plug-like body is inserted into the ventilation path from an outside of the cylinder body. (See Patent Document 1)
In such a damper device, a forward movement of the piston body in a direction separating from the closing portion is allowed by an air intake through the ventilation path. As a forward movement speed of the piston body is faster, a difference in pressure between an inside and an outside of the cylinder body becomes greater, so that an insertion length of the shaft portion into the ventilation path increases. The more the insertion length increases, the more difficult the air intake through the ventilation path is carried out, so that a force necessary for the forward movement of the piston body, i.e., a braking force generated from the damper device, increases.
However, in such damper device, the ventilation path is formed by a tube-like portion protruding into the cylinder body from the closing portion by allowing one end of a tube to be communicated with a through hole formed in the closing portion of the cylinder body, so that in a position wherein the piston body has most approached the closing portion of the cylinder body, it is not necessarily easy to minimize a space generated between both members. If such space cannot be minimized, as soon as the forward movement in the direction separating from the closing portion starts from the position where the piston body has most approached the closing portion of the cylinder body, it becomes difficult to generate a change in pressure in such a way as to increase the insertion length of the shaft portion of the plug-like body into the ventilation path so as to deteriorate responsiveness of an initial movement of the damper device.